Aboard A U.S. Military Aircraft (AP) - The United States is considering speeding up its withdrawal from Iraq because of the sustained drop in violence there, Defense Secretary Robert Gates said Wednesday following discussions with his top commanders in the war.

"I think there's at least some chance of a modest acceleration," this year, Gates said.

It was the first suggestion that the Obama administration might rethink its difficult choice to leave a heavy fighting force in Iraq long past the election of an American president who opposed the war.

Gates said the consideration came because the situation is "better than expected."

Perhaps one of the current 14 combat units could come home early, Gates said, which would mean a cut of roughly 5,000 people.

Continued bad blood between Iraq's Arab-led central government and the self-ruled Kurdish region in the north represents the major wild card to a faster pullout, Gates spokesman Geoff Morrell said.

Concern is growing that North-South tensions over land and resources could become a shooting war once U.S. forces leave. Gates spent much of his two-day visit in Iraq warning both sides that U.S. forces will not be around to keep the peace forever, and he offered U.S. help to mediate.

"These are some fundamental issues, and I think it's important that both the government in Baghdad and the Kurds have pursued them through political means" so far, Gates told reporters after meeting Kurdish President Massoud Barzani in Irbil, capital of the Kurdish self-rule area.

Gates said he told his hosts all sides had spent "too much in blood and treasure" since the 2003 U.S. invasion to risk losing it now.

The United States has about 130,000 forces in Iraq, with current plans calling for most combat forces -- or more than 100,000 troops -- to remain in the country until after Iraqi national elections in January.

Gates gave no other specifics, and stressed that the idea is preliminary and tied to continued good news in Iraq.

"It depends on circumstances; it may or may not happen," he said.

The top U.S. commander in Iraq, Gen. Ray Odierno, raised the possibility during Gates' two-day trip to Iraq. If Odierno follows up with a formal recommendation, it would come sometime this fall.

It was largely because of Odierno's worry that the coming Iraqi election would trigger a rebound in violence that President Barack Obama decided on a very slow withdrawal. The decision, announced in February, disappointed many anti-war Democrats.

Under the current plan, the United States would draw down from 14 brigades to 12 this year. After the January election, the withdrawal pace would quicken, leaving about 50,000 forces in Iraq by September, 2010.

Violence is ebbing in Iraq, and Odierno said Tuesday that he has been pleasantly surprised at how few problems have arisen following a June 30 handover of control of Iraqi cities.

American military commanders say friction between Arabs and Kurds in northern Iraq is the greatest threat to security in the country, overtaking the old Sunni-Shiite divide that threatened to push Iraq into civil war three years ago.

The relatively affluent, peaceful Kurdish North is feuding with al-Maliki's government over its borders and resources. Gates met with Barzani, who claimed victory in a re-election vote last weekend that also saw large gains by an opposition slate, in Irbil, seat of the regional government.

Morrell said the U.S. military has advisers already serving as go-betweens for the Kurdish militia and Iraq's armed forces.

Gates told Barzani that the U.S. backs a set of United Nations recommendations to resolve some of the major disputes. Morrell would not characterize Barzani's response, except to say that Gates left the meeting "with the sense, just as he did in Baghdad, that the Kurds very much want to take advantage of our presence."

Odierno identified the tension in northern Iraq as the "No. 1 driver of instability."

"Many insurgent groups are trying to exploit the tensions," Odierno told reporters Tuesday. "We're watching very carefully to see that this doesn't escalate."

So far, American intermediaries are helping keep a lid on things, Odierno said.

The Kurds have been locked in a dispute with Baghdad over control of oil resources and a fault line of contested territory in northern Iraq, particularly the flash-point city of Kirkuk. The disagreements have stalled a national oil law considered vital to encouraging foreign investment. U.S. officials have warned that Arab-Kurdish tensions could erupt into a new front in the Iraq conflict and jeopardize security gains elsewhere.

Kurdish leaders say they are committed to staying in a unified Iraq, particularly since an independence push could alienate neighboring Iran, Syria and Turkey, which have their own Kurdish minorities. But Iraqi Kurdish politicians must answer to the strong nationalist sentiment among Kurds.

Reformist candidates did better than expected against two established Kurdish political parties in weekend elections, adding to the uncertainty. The reformist slate, called Change, tapped into widespread frustration over alleged corruption and intimidation by the longtime ruling establishment.

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